Small-scale electric generation, such as backup, standby and emergency generators, are used in many locations. The electric generators must be maintained by an operator to monitor fuel, oil and temperature levels. In some cases, alarms might alert the operator that the electric generator might be running low on fuel. However, by the time the operator becomes aware of the low fuel condition, the electric generator could run out of fuel before fuel supplies are replenished and/or may not be able to safely shut-down electrical loads before a power system disruption.
Fuel level detectors for warning an individual of a low fuel supply are well known. For example, a Hara, U.S. Pat. No. 4,175,435 discloses a liquid level detection device. As disclosed a liquid level detection device comprises an annular float adapted to float constantly on the surface of a body of liquid subjected to level detection, a barrel passing through the float to guide the motion of the float, permanent magnets disposed in the float and a magnetically operable lead switch disposed in the barrel permits the detection of the liquid level. The device works on the principle that the lead switch is magnetically turned into it's on state at the time that the float while in motion reaches the position at which the barrel incorporates the switch.
A more recent patent of Wickman et al., U.S. Pat. No. 6,253,742 discloses a method for controlling the operation of a fuel system that uses a lift pump. The system uses a lift pump to transfer fuel from a remote tank to a vapor separator tank. Only one level sensor is provided in the vapor separator tank and an engine control unit monitors the total fuel usage subsequent to the most recent filling of the tank. When the fuel usage indicates that the fuel level in the vapor separator tank has reached a predetermined lower level, a lift pump is activated to draw fuel from a remote tank and provide that fuel to the vapor separator tank.
Notwithstanding the above, it is presently believed that there is a need and a potential commercial market for a protection system for an electric generator in accordance with the present invention. There should be a demand for such systems for use with electrical generators to protect the generators from running out of fuel and shutting down prematurely.